Variable-capacity compressor



March 5, 1929. M R|E5NER 1,704,343

VARIABLE CAPACITY COMPRESSOR Filed Sept. 17, 1926 MIcHAEL RIESNER.

l IOR ATTORNEY vPatented. Mar.' 5,- 1929.

- UNITED VSTATES' PATE A14,704,343 NTA oFFicE.,

MICHAEL BIESNER, OF CINCINNATI; OHIO, .ASSIGNOR TO WORTHINGTON PUMP .AND MACHINERY CORPORATION, OF NEW YORK, N. Y., .A CORPORATION OF VIRGINIA.

'VARIABLE-CAPACITY Application led September 17, 1926.` Serial No. 136,009.

This invention relates to means for unloading fluid compressors and broadly to meansv for automatically unloading the compressor,

an apparatus of this type Which shall be economical in operation, `provideV a relatively high eiliciency compressor, and one which Will be relatively simple in construction and consequently cheaper to manufacture than those heretofore used. y Y,

The present invention contemplates the use in a variable capacity compressor, of clearance chambers and a by-pass port connected in series which permit, with the othermechanisin, the gradual unloading and loading .of the compressor cylinder for permitting its operation under various predetermined percentages ofits full capacity.

For a full un'derstandingof the invention, a detailed description of a construction einbodying the s ame in a preferred form Will novv be given in connection with the accompanying `drawing forming a part or this' specification and Which shows in section and partly in elevation a variable capacity compressor and its regulator or control con structed in accordance with this invention, and the features forming the invention then specifically pointed out in the claims. y

Referring more particularly to the d rawing, A is the compressor cylinder, B thepiston and C the piston rod VWhich is driven in any suitable manner, and While no suction or discharge valves areshown in the drawings it is to be'understood that the compressor is pro-v vided With suction and discharge valves, of approved type, at the crank and head ends oi the cylinder A as is usual in the construction oi double acting compressors of approved types. L

A clearance chamber 1 is provided at the head end of the cylinder A and va second clearance chamber 2 is positioned contiguous to the clearance chamber 1 and has direct communication with ayby-pass port 3 which eX- tends along the cylinder A t0 the crank end thereof.

The clearance chamber 1 has communica-` tion with the interior of the cylinder A through a port `4 which is controlled by. a valve actuated by a pressure-operated piston 11 which is moved in its cylinder 12 by receiver pressure to open the valve for connecting the cylinder .with the clearance chambenl and partial unloading and is closed by spring 13. Fluttering of the valve 10 is prevented by the spring 14 Which engages the piston 11 on its side oppositev from that engaged by the closing spring 13. y

The clearance chamber 2 is connected to the clearance chamber l by a port 21 which is closed by a'valve 22, andhas direct connection with the by-pass port 3. rI'he by-pass port 3 has connectionwith the interior of the cylinder A at the crank end of the' cylinder, through aportBO which isl controlled by a valve 3l. The valves 22 and 31 are actuated by pressure-operated pistoiis 23 and 33 re-y spectively which are moved by receiver pressure to open the valves to partial and complete unloading of thecylinder A and are closed by springs 24 and 34 respectively. v ,f

The pistons 11,23 and 33 are automatically C,controlled by the control apparatus D and pressure is applied to the inner side of the piston .11, through the passageway 15, to open the clearance valve 10 for the rst unloading` step, by receiver pressuretransmitted through the pipe la, Pressure is applied to the inner side of the piston 23 through the pipe 2a to open the valve 22 for the second unloading step; and receiver pressure is applied to the inner side of the piston 33 through the pipe 3a oropening the valve 3l' for the third or final' unloading step at which time the compressor will operate at zero capacity. l

Adinittance of pressure to the pipe l, 2a and 3 and consequently to thepistons 11, 23 and 33 is controlled for unloading and loadJ ing, by a piston valve 40, which is actuated by apparatus controlled by the receiver pressure, as usual in such unloading'VV devices, and ,this

receiver pressure and operation of the,I valve able character and taken from any suitable source, thus enabling the 'apparatus D to be controlled by slight variations in the receiver pressure, while employing pressure as heavy as desired for actuating the piston 41. .The control apparatus just generically "described is more fully illustrated and specifically described in m rior Patents'- numbered 1,579,781 and 1,579,782.

The clearance chambers may be of any desired capacity so as to unload and load the cylinder in the steps required, kbut assuming that the capacity of each clearance chamber tis` such as to provide a one-third unloading of the cylinder, the operation ofthe construction shown and above described, is as follows: Assuming that the compressor is operating at full capacity, an increase in receiver pressureabove that for which the apparatus is set will raise the lever 43 and operate the pilot valve 42 so as to admit pressure fluid through the passage 47 against the right end.

of the piston 41 and connect the other end of the cylinder 48, in which .the piston 41 moves, with the exhaust 49, and thus move the piston 41 to the left, in the drawing, untilthe cut ofi' end 50 of the piston valve 40 passes the port of the pipe 1a, when the fluid jwhich is admitted tothe cylinder 51, under receiver pressure, through the pipe 52, w1ll pass through the pipe 1a to the inner side of the p-iston.^11 and open the valve 10 to connect the compressor cylinder A with the clearance chamber 1, at which time the compressor will operate at 7 5% capacity. vThe control apparatus now returns the pilot valve 42 to its normal position, preventing inlet to 5 or exhaust from the cylinder 48 and stopping the piston 41 in this position.

. On a further increase of receiver pressure the samev operation is repeated except that the piston valve is lmoved forward another step and opensup communication with the pipe 2a topermit opening of the valve 22 by movement of the piston 23, which opens up` \the clearance chamber 2 and by-pass port 3 to the clearance chamber 1 and through the chamber 1 to the cylinder A, thus fully unloading the head end of the cylinder A so that the compressor operates at 50% capacity.

On a still further increase of receiver pressure'the same operationl is 4again repeated, this time m'oving the piston valve 40 another vstep so as to permit the fluid under receiver pressure to flow through theypipe 3a and move the piston 33'for opening the valve 31,

thus opening the crank end of the cylinder A to the by-pass port 3and through the chambers 2 and 1 to the head end of the cylinder for completely unloading bothends of the cylinder so that the compressor operates at zero capacity. f

Decrease in receiver pressure permits the weighted lever 43 to fall, and reverses the above operation, the compressor being graduallyloadedin the same proportions of its (full capacity as those in which it is unloaded;

i. e. upon the decreasein receiver Ipressure the piston valve 40 is moved one stepto the right, in the drawing, and cuts off communication between the pipes 52 and 3al and relieves the piston 33 of' pressure, the pressure fluid bleeding from pipe 3av through the open end of the cylinder 51, which permits the spring 34 to seat the valve 31 and permits operation of the compressor at 50% capacity.

As the receiver pressure further decreases the piston valve 40 is moved to the right, in the drawing, to successively cut off flow of pressure fluid to pistons 23 and 11 and pernit seating of the valves 22 and 10 and the ompressor then operates, first at 75% ca- )acity while only the lvalve 22 is seated, and Vhen at 100% or full capacity when the valve 10 is seated.

From the foregoing Vdescription taken in connection with the accompanying drawing it will be apparent that the present invention provides an efficient variable capacity compressor of extremely simple construction vin Which the compressor cylinder is gradually Sunloaded, and loaded by successive opening to and closing from the lcompressor cylinder of the clearance chambers 1 and 2 and bypass port 3, and it will be noted by reference to the drawing that the clearance chamber 2 is in fact a part of the by-passvport 3 and that the latter operates as a clearance chamber when only the valves 10 and y22 are open, coming into operation as a by-pass port when the valve 31 is opened. l

The cylinders in which the pistons 11, 23 and 33 operate may be connected by a pipe 36 to a low pressure such as the intercooler Ipressure in a multiple stage compressor.

It will be understood that the invention-is not limited to the specific form or arrangement of parts illustrated, but that many Yunodifications may be made therein while retaining the invention defined by the claims.

What is claimed is 1. In a variable capacity compressor, the

combination with a cylinder, of a plurality' of clearance chambers in the head end of the cylinder, a passage connecting one or more of said clearance chambers with the crank end ofthe cylinder, and pressure controlled means for partially unloading the head end ofY said cylinder`by one of said chambers, wholly unloading the head end by the clearance chambers, and wholly unloading the cylinder by said clearance chambers and passage.

2. In a variable capacity compressor, the combination with a cylinder, of a clearance chamber at 'the head end of the cylinder, a by-pass port extending along the cylinder and having connection at its oppositey ends with saidclearance chamber and the crank end of the cylinder respectively, and pressure controlled means for partially unloading the head end of the cylinder by said clearance chamber and fully unloading the head end of the cylinder by said clearance chamber and by-pass port. l

3. In a variable capacity compressor, the combination With a cylinder, of a clearance chamber at the head end of the cylinder, a bypass port extending along the cylinderv and having connection at its-opposite ends With said clearance chamber and the crank end Ot' the cylinder, pressure controlled means for partially unloading the head end of the cylinder by said clearance chamber and fully unloading the head end of the cylinder by said clearance chamber and by-pass port, and unloading the crank end of the cylinder by said by-pass port.' Y

4. In a variable capacity compressor, the combination with a cylinder, of means ior gradually unloading the cylinder comprising a clearance chamber at the head end of the cylinder and a by-pass port along the cylinder, and having connection at its opposite ends with said clearance chamber and the crank end yoit' the cylinder and pressure operated means for partially unloading the head end of said cylinder by said clearance chamber and Wholly unloading the head and crank ends of the cylinder through said by-pass port and clearance chamber.

5. In a variable capacity compressor, the combination with a cylinder, of a plurality of clearance chambers in the head end of the cylinder, pressure operated means for opening one of said chambers to said head end for partly unloading the head end, and pressure operated means for connecting said clearance chambers for further unloading said head end.

6. In a variable capacity compressor, a combination with a cylinder, of a plurality of clearance chambers in the head end of the cylinder, pressure o erated means for opening one of said cham ers to said head end for partly unloading the head end, and pressure operated means for connecting said clearance chambers for further unloading said head end, a passage connecting said second chamber with the crank end of the the cylinder, and pressure operated means controlling connection of said passage and crank end.

7. In a Variable capacity compressor, the combination with a cylinder, of a clearance chamber in the head end of the cylinder, pressure operated means for opening said clearance chamber to the cylinder for partly unloading the head end of the cylinder, a bypass port, pressure operated means for opening said by-pass port to said clearance chamber for further unloading of the head end of the cylinder, and pressure operated means for opening said by-pass port to the crank end of the cylinder for wholly unloading the cylinder.

In testimony whereof I aix my signature.

MICHAEL RIESNER. 

